Method of and apparatus for treating wells



June 15, 1943. o. BARSTOW METEOD AND APPARATUS FOR TREATING WELLS Filedu 28, 1940 2 Sheets-*Sheet 1 FIG.

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ATTORNEYS.

Patented June 15, 1943 UNITED STATES PATENT OFFICE METHOD OF ANDAPPARATUS FOR TREATING WELLS Onnond Bax-stow, Midland, Mich, assignor toThe Dow Chemical Company, Midland, Mich, a corporation of MichiganApplication August 28, 1940, Serial No. 354,509

7 Claims. (01. ce-2) The invention relates to a method of and -D-paratus for treating wells, such as oil, gas, brine, or water wells, andmore particularly concerns a method whereby a fluid treating agent maybe simultaneously introduced into two ,or more zones penetrated by thebore of a well while said zones are sealed off or separated from oneanother in such manner that the fluid agent in the well bore about toenter one zone is maintained out of contact with the fluid treatingagent in the well bore about tov enter the other acne.

The bore of a well oftentimes penetrates more than one producing stratumor zone, and it is usually desirable when treating such wells with afluid treating agent to be assured that some of the treating fluid willbe iniected into each zone.

In some instances it is even desirable to closely control the amount oftreating fluid that is injected into each zone. For example, in thetreatment of more than one productive zone in calcareous earth or rockto bring about an increase in production by the use of an acid, it maybe desirable that a method of treatment he provided to positively insurethat each zone will receive a definite proportionof the acid, forotherwise most of the acid may drain into the zone having the mostporous structure, with the result that the most effective increase inproduction will not be obtained from the section or sections having thesmaller pore spaces or voids. It is further desirable, when treatingsuch wells, that the introduction of fluid agent into each zone takeplace simultaneously in order to-avoid carrying out a separate treatmentof each zone. The term zone, used herein and in the appended claims,refers to separately defined strata as well as sections or portions of asingle stratum or formation. 1

It is, therefore, the principal object of the invention to provide amethod and apparatus whereby a fluid treating agent may besimultaneously introduced into each of at least two zones penetrated bythe bore of a well.

Another object of the invention is to provide a method and apparatuswhereby a fluid treating agent may be simultaneously introduced into atleast two zones at a preselected ratio of rates of flow.

Other objects and advantages will beapparent as the description of theinvention proceeds.

The invention, then, resides in the method hereinafter more fullydescribed and particularly pointed out in the claims, the accompanyingdrawings and following description setting forth in detail a mode ofcarrying out the invention,

such mode illustrating. however, but one of the several ways in whichthe invention may be put into operation.

In the accompanying drawings:

Fla. 1 is a fragmentary view of a well bore in vertical cross-sectionshowing one embodiment of the invention.

Fla. 2 is a fragmentary sectional view of Fig. 1 showing that section ofconduit 9 which includes the discharge port II and illustratesadditional elements associated with the discharge p rt, which actto'modify-the operation of the apparatus.

P18. 3 is a fragmentary view of a well bore in vertical cross-sectionshowing another embodiment of the invention which may be suitably usedin place of the apparatus illustrated in Fig. 1.

Fig. 4 is a cross-sectional view taken along the lines H of Fig. 3looking in the direction of the arrows. 7

Referring more in detail to Fig. l, the upper portion of the well boreis cased with metal pipe I, which is cemented in place about its lowerend by cement 2. The lower portion 3 of the well bore penetrates aproductive stratum 4, an impervious stratum 5, and ends in a secondproductive stratum 8. Attached to the well tubing 1 by means of acoupling 8 a short conduit 9 is shown provided with a discharge port itat a point adjacent the pper productive stratum 4. The lower portion ofconduit 9 ends in an inwardly projecting flange H, which serves as aseat for the body member l2 housing the fluid flow control element. Thebody member I2 of the control element is provided with an outwardlyprojecting flange M, which engages inwardly projecting flange ii ofconduit 8 and is securely held thereto by means of bolts I3. The housingof the control element comprises two separate symmetrical sections.which are secured to each other at flanges l5 by bolts 16. In addition,flanges I5 and bolts i6 act to support and hold diaphragm H in positionso that it divides the body member of the control element into twocompartments. The diaphragm I1 is of corrugated or bellows-likeconstruction andis thus adapted to move laterally as pressure in onecompartment builds up in excess of that in the other compartment. Thediaphragm I1 is provided on either face with cen-' trally locatedtapered plug members 18, which are adapted to engage complementallytapered shoulders on the fluid outlet or discharge ports vided withthreaded bosses 22 and 23 into which threaded orifice members 24 and 25screw, serving as inlet ports for the fluid entering the left and rightcompartments of the control element. Discharge port IS in the leftcompartment of the control element communicates with the well borethrough conduit 26; while discharge port 20, provided in the rightcompartment, communicates through conduit 21 with the interior oftubular element 28 attached to the lower end of conduit 9 by means ofconventional coupling orcollar, in-

, dicated by numeral 8. The tubular element 28 extends into the well andacts to support conventional packer 29, shown in seated engagement withthe well bore against impervious stratum 5. Below the packing element,tubular element 28 extends further into the well and is sealed off withcap 30 at its lower end. The tubular member 28 is provided with a port3| below the packing element 29, which'serves as a'means wherebypressure applied interiorly of conduit 28 overcomesvthe pressure of thespring 35, acting to force the valve out of sealing relationship againstdischarge port I 0.

In the embodiment shown in Fig. 3, the well tubing I extends into thewell'and engages a conventional coupling 8. The coupling serves to ingwith the left compartment of the control elevment, discharges throughconduit 53 and port 54 into the well bore at a point adjacent the pro-'*ductive stratum 4. The port 44, communicating with the rightcompartment of the control element, allows the fluid to flow intoconduit 55,

and thus into the stratum below the packer.

Conduit 55 acts to support conventional packing element 29, also shownin Fig. 1, which is in seated engagement with impervious stratum 5.Below the packing element the conduit 55 extends further into th welland ends in conventional cap member 56. A port 51 is provided in conduit55 below the packing element 29, and serves as a means whereby the fluiddischarging from the right compartment of the control element can flowinto lower productive stratum 5.

In Fig. 4 the relation of plate member 48 and the associated piston andcylinder is more clearly shown.

The method of the invention will be best understood'from the followingdescription, wherein the apparatus illustrated in Fig. l is employed tocarry out an acid treatment for the simultaneous injection of acid intostrata 4 and 6. With the apparatus assembled as shown, well tubing I islowered 'into the well boresoas to position the packing element oppositeh' pervious stratum 5. 5 The packer is the i as to separate productivestratum ductive stratum 6, and a quantity ar id ""ot shown) isintroduced into the wellth'r ug the tubing 1. Pressure is then appliedto-th acid as by pumping;an'additionalquantity the well through thetubing'l; At the sam me,

. lar spaceext'erior of thewell tubing, so esteemattach well tubing 1 toa short tubular element 31, which acts as a. housing for a fluid flowcontrol assembly adapted to accomplish the same results as the apparatusof Fig. 1. The tubular element 3'! is provided at its upper end with aplate 38 having threaded bosses 35 and 40, which engage removableorifice plug members ti and 42. The'plate 38 is secured and sealed aboutits peripheral edge to the tubular element 31, as by means of a weld.The lower end of tubular element 3'! is likewise provided with a plate43 having discharge outlets 44 and 45, and is secured to tubular element31 in a manner similar securely held thereon; by means of plate 48extending in a direction transverse of that of the cylinder, as shownmore particularly in Fig. 4. The plate 48 is sealed and secured to thetubu lar element 81 and plate members 38 and 43, as

' well as cylinder-4'6, by welding, and thus divides the interior oftubular element 31 intotwo compartments. Set screws 49 threade'dlyengage bosses 50 in either wail of tubular element 81 at points oppositethe ends of piston 41, and act as stop members for the piston as itslides in the cylinder 40. The cylinder 46 is provided with 1 dischargep rts 5! and 52, which are adapted to register with ports 44 and in thelower plate member 43. The discharge port 45, communicattrol the levelto whichthe acid solution can rise in the well bore as it escapes fromthe discharge port it in conduit 9. Acid entering'the conduit 9 isdirected into each compartment of-the control element through the inlet"ports in orifice 1 members 25 and 25. The fluid agent entering the leftcompartment is forced therefrom through port is, conduit 2E and-port itinto the well bore adjacent stratum 4. The fluid entering the rightcompartment of the control element is forced therefrom through dischargeport 20 and conduit 21 into conduit-'28, and thereafter out into thewell bore below the packer through port 3|. The orifice size in inletorifice members 24 and 25 is conveniently chosen so that a pressure dropcan readily be maintained across the orifices during the introduction ofthe fluid agent. By varying the diameter of the orifices, more or lessacid can, of course; be directed to a selected zone. After the desiredquantity of acid has been introduced, it may be displaced from theinterior of'the well tubing and conduit ii by pumping a quantity-of oilor the like into the well through said tubing.

During the introduction of the fluid agent, the

control assembly functions to regulate the rate v of flow of fiuid bydirecting fluid to each stratum at a rate approximately proportional tothe crosssectional area of the orifices or ports 24 and 25 in theorifice members, since the pressure in .the

two compartments is maintained substantially equal at all times duringthe treatment by the diaphragm actuated plug members. For example, if atany time during the introduction of the fluid agent one stratumrequi'resa higher;

highest pressure to force fluid thereinto, causing the diaphragmactuated plug members to partially seal thedischarge outlet in the othercompartment, so as to bring about an equalization of pressure'in the twocompartments. Since the pressures in the two compartments, and thereforethe pressure-dropsacross thev twooriflces,

are at all times substantially equal, the ratio of rates of flow to thetwo strata is substantially equal to the ratio of areas of the inletorifices- 24 and 25. This fixed ratio of flow rates to the two stratacan be set at a predetermined value by installing orifices 24 and 25having the desired area ratio in the control apparatus before it isplaced in the well.

. lets are restricted relative to the inlets. It is desirable to selectthe inlet orifices of such as size that it is possible toreadily'maintain a pressure drop across them of such order that thepiston or diaphragm operated plug members will be actuated to controlthe flow of fluid.

If desired, the spring loaded back pressure valve assembly illustratedin Fig. 2 may be employed by attaching said assembly to either of thefluid discharge outlets. The back pressure valve assembly or the like,associated with the discharge ports or outlets, may be advantageouslyused in some instances, as for example, to correct for differences information pressure between the various zones that may be encountered.Such correction maintains each compartment of the control elementatamore nearly equal pressures, allowing the diaphragm or piston to takea more central position than they otherwisecould where wide differencesin pressure exist between the various zones.

Similarly, the method of the invention may also be suitably carried outemploying the modification illustrated in Fig. 3, which is also adaptedto direct fluid to each stratum at a rate directly proportional to thediameter of the fluid inlet orifices. In the apparatus illustrated inFig. 3, the piston 81 functions in a somewhat similar manner to thediaphragm member carrying the plug members illustrated in Fig. 1. Forexample, when the fluid pressure becomes greater in one compartment thanthe other, the piston moves to relieve the pressure, and, by partiallysealing of! one of the discharge outlets, acts to equalize the pressureso that the same pressure exists in both compartments. This in turninsures that fluid will flow to each stratum at a rate directly proportional to the size of the oriflce communicating therewith, since thepressure drop across the two orifices is kept equal.

Themethod will be found to have most general use in connection with anacid treatment wherein asolution of hydrochloric or other acid isintroduced into the formation to bring about solution of the earth orrock formation and thus an increase in size of the flow channels throughwhich the desired mineral fluid flows to the well. In such treatments itwill usually be found prelbe introduced in accordance with the method ofthe invention. Examples of such treating agents are paraflin solvents,liquid sealing agents, and the like.

In the above manner a fluid treating agent such as an acid may besimultaneously introduced into two or more strata or zones with theassurance that each formation will receive a more satisfactory treatmentthan is the case if the conventional method is employed wherein the borehole is merely fllled with the treating fluid and pressure appliedthereto to force the treating fluid into each stratum at a. ratedependent only upon the ability of the formation to receive the fluidagent.

I claim: s

1. In a well treating device for the simultaneous injection of a fluidagent into at least two zones penetrated by the bore of a well, thecombnation of a conduit adapted to be disposed in the well bore, sealingmeans surrounding said conduit adapted to seal the annular space betweenthe conduit and the well bore at a point between said erable to employan aqueous solution at hydrozones, fluid control means carried by theconduit having restricted fluid entry ports and discharge ports therein,with the discharge ports in communication with the zones above and belowthe sealing means, said control means being adapted to maintainsubstantially equal pressures at the discharge ports so as to direct thefluid agent to each zone at a substantially fixed ratio of rates offlow.

2. In a well treating device for the simultaneous introduction of afluid agent into at least two zones penetrated by the bore of a well,the combination of a conduit having spaced openings therein, sealingmeans surrounding said conduit between said openings, and adapted toseal the annular space betweenithe conduit and the well bore at a pointbetween said zones, a fluid flow control devioe-sealed in said conduithaving restricted ports for the entry of fluid into the interior thereofand fluid discharge ports which movable member dividing the fluid flowcontrol device into two compartments waled from each other so that a.restricted fluid entry port and e fluid discharge port communicate witheach compartment, said movable member being adapted to engage the fluiddischarge ports in sealing relationship as the movable member is causedto move in response to pressure building up in one compartment in excessof that in the other compartment.

3. In a well treating device for the simultaneous injection of a fluidagent into at least two zones penetrated by the bore of a well, thecombination of a conduit having spaced openings therein, sealing meanssurrounding said conduit at a point between the openings adapted to sealthe annular space between the conduit and the well bore at a pointbetween said zones, a fluid flow control means sealed in said conduithavin restricted ports for entry of fluid into the interior thereof andfluid discharge ports communicating respectively with the spacedopenings in the com duit above and below the sealing means, a movablediaphragm member dividing the interior of the control element into twocompartments sealed from each other so that a fluid entry port and afluid discharge port communicate with each compartment, and a plugmember carried by the movable diaphragm adapted to engage the fluidpressure building up in one compartment in excess of that in the othercompartment.

4. In a well treating device for the simultaneous injection of a fluidagent into at least two zones penetrated by the bore of awell, the

in an opening in said plate member adapted to and below the sealingmeans, said fluid control means being adapted to respond to the pressurerequired to force the fluid agent into each zone so as to direct thefluid into each zone at a rate substantially proportional to the area ofthe restricted entry ports.

5. In a well treating device for the simultaneous injection of a fluidagent into'atleast two zones penetrated by the bore of a well, thecombination of a conduit having spaced openings therein, sealing meanssurrounding said conduit adapted to seal the annular space between theconduit and the well bore at a point between the openings, a fluid flowcontrol device sealed in said conduit having restricted ports for theentry of a fluid into the interior thereof and fluid exit portscommunicating respectively with spaced openings above and below thesealing means, a plate member dividing the interior of the controlelement into two compartments, apiston disposed move in said opening soas to curtail the flow of fluid to one of the exit ports as the pistonis 7 caused to move by pressure building up in one compartment in excessof that in the other compartment.

6. The apparatus of claim 1, wherein a spring loaded back pressure valveis associated with one of the spaced openings in the conduit.

7. In a well treating device for the simultaneous injection of a fluidagent into at least two zones penetrated by the bore of a well, thecombination of a conduit having spaced openings therein, sealing meanssurrounding said conduit adapted to seal the annular space between theconduit and the well here at a point between the openings, an enclosedfluid flow control element sealed in said conduit having restrictedports for the entry of a fluid int'o the interior thereof and fluid exitports communicating respectively with spaced openings above and belowthe sealing means, a piston disposed in the control element and dividingthe interior thereof into two compartments so that a fluid entry portand fluid exit port communicate with each compartment, said piston beingadapted to move in the control element to engage the fluid exit ports insealing relationship without sealing the fluid entry ports as the pistonmoves by pressure building up in one compartment in excess of that inthe other compartment.

ORMOND BARSTOW.

